The invention is directed to a contacting mechanism for micro-electronic components, particularly LSI circuits, to be tested and having a large number of poles. The contacting mechanism is in the form of a needle card having a plurality of contacing needles corresponding in number to the plurality of contacts of the component to be tested.
Modern micro-electronic components, such as, for example, LSI circuits as a chip on a silicone wafer, must be contacted by testing equipment such that the contacting mechanism itself only generates slight electrical disturbances (such as, for example, series inductances, grounded capacitances and electro-magnetic couplings as well as ohmic contact resistances). Only then can the electrical properties of the component be faultlessly measured. Error-free measurements at sub-nano second circuits and chips, however, are difficult to execute or cannot be executed at all with traditional contacting mechanisms because the LSI components are being increasingly given finer and finer contact divisions. A contacting with the hitherto standard design and dimension of individual springs thus has structural limits and generates electrical disturbances. A contacting by employing flexible printed circuits in combination with an elastic pressure pillow does not necessarily lead to uniform contacting forces for all contacts. This also encounters difficulties for yet another reason. When the number of contacts of the component to be tested is so high that they can no longer all be arranged in a single row at the edge of the component, it has not been hitherto possible to utilize flexible printed circuits that could be contacted to the contact spots of the components arranged in a plurality of rows following one another. The chip contacting on wafers is therefore currently still carried out with sensing needles.
A number of solutions have been disclosed for the fashioning of such contacting mechanisms having a plurality of sensing needles, which are provided in what is referred to as a needle card, corresponding in number to the plurality of contacts of the component to be tested. Thus, for example, it is known to provide contacting needles freely projecting in a downward direction at an angle away from the edge of the inner opening of the needle card, these contacting needles respectively pressing against the respective contact spots of the component with a free end that is bent downwardly away. Due to the slight distances between the contact spots of the components and their dimensions, which are extremely small, the manufacture of such a contacting mechanism is extraordinarily difficult given a contacting mechanism for testing components having an extremely high number of poles.
It has been proposed to guide those ends of the contact needles serving the purpose of contacting in guide holes of a plate which is arranged above the component to be tested. The needles project away from this plate bent slightly in upward direction and are embedded in a shared block at their end. As a result of the slight bending of the needles, the needles can deflect somewhat laterally when pressed against the component to be respectively tested and thus enable a resilient contact pressing. The disadvantage of this arrangement is that the contacting needles do not lead upwardly away from the needle card in the direction of the needle card, but perpendicularly thereto and thus generate great electrical disturbances as a consequence of their length and position. Further, a replacement of individual needles is not possible at all if they are damaged in this contacting mechanism.
It has also been proposed to guide the individual contact needles in small, thin tubes which are all cast with one another in what is referred to as a contact block and, thus, reliably hold their spacings. The disadvantage of these contacting mechanisms is that the cross-section of the needles must be greatly reduced given a slight spacing between the contacts of the component to be tested since, of course, they are also guided in the small guide tubes. Further, the contacting between needles and guide tube is unreliable. Since all small guide tubes are cast out in the contact block, the replacement of individual needles is possible, but the replacement of damaged guide tubes is not possible.